Front Won't Build Pressure

[j_wahl91]

Well, that's a big kick in the nuts. During my ride yesterday, my brakes were quite good, and today they were much worse, ziptied the lever after a quick test ride, and an hour later, the lever's dead. No pressure at all..

Something tells me the dancing bananas jinxed it. Either that or Jim has a voodoo doll of your ride and he's been playing poke the brakes on it

[robertv]

Silly question, but checking to be sure- you are using DOT 4 brake fluid? Synthetic or not?

[okrider]

I blame the bananas too. Using DOT4, synthetic I'm pretty sure. It's valvoline brand

[turbojoe78]

You comment quite often about zip tying the lever after you have problems.  Have you tried just bleeding and not zip tying?  Could zip tying the lever down, keeping constant pressure on the brake system have anything to do with your problems?

The normal state of the system when not in use is relaxed, no pressure on pads or calipers.

[okrider]

I have tried bleeding and not ziptying, the pressure was a little less, but there was some pressure when I did that.

It's common practice to ziptie the lever shut overnight to let air bubbles escape. It also tells you if there's a problem with the system which seems to be the case with mine.

[connie_rider]

Ok, ok, Ohhhhtay!! I'll take the heat...
It's my fault.
No more dancing banana's..

       

Ride safe, Ted

[VirginiaJim]

You know, nothing else was cracked open but the master cylinder and the calipers.  It's got to be something with the caliper rebuild.  I hope that the 'new' ones help you out and you can put this to bed.

[Freddy]

It's common practice to ziptie the lever shut overnight to let air bubbles escape. It also tells you if there's a problem with the system which seems to be the case with mine.

That's an old wives' tale.  From where do bubbles escape?

[okrider]

they rise to the master reservoir? Either way, it's supposed to be able to hold pressure overnight

[connie_rider]

Freddy, someone accidentally discovered that storing with the levers partially compressed overnight allowed the system to improve. 
Many (including me) have tried it {on a hard to bleed system} and it does seem to help.
The only think I can think of that seems to make sense is; pulling the lever back compresses' the trapped air, and opens a valve in the master cylinder that allows compressed air to migrate up into the reservoir.

Ride safe, Ted

[kzz1king]

I have used this method for years and it seems to help. I just changed pads in my 14 and the front didnt seem like it wanted to pump up like it should, just came back closer to the bar than it should. I pumped it up and put an small bungee on it and it seems good now. At any rate it did not get any closer to the bar under pressure because I measured the space in the evening and then the next day.
Wayne

Freddy, someone accidentally discovered that storing with the levers partially compressed overnight allowed the system to improve. 
Many (including me) have tried it {on a hard to bleed system} and it does seem to help.
The only think I can think of that seems to make sense is; pulling the lever back compresses' the trapped air, and opens a valve in the master cylinder that allows compressed air to migrate up into the reservoir.

Ride safe, Ted

[Freddy]

they rise to the master reservoir? Either way, it's supposed to be able to hold pressure overnight

That's not so.  Any air trapped in the line cannot escape/rise into the reservoir because the port thru which it would enter the reservoir is closed when the lever is moved from the released position.  Check how a master cyl works.

It may allow any air to rise to the master cyl so that when the lever is released, it immediately enters the reservoir.

[kzz1king]

I had to check it out and you are correct. Now you have me wondering if its  all in my head or does it work. Maybe its the constant pressure on the bubbles and than they are released like you mentioned.

That's not so.  Any air trapped in the line cannot escape/rise into the reservoir because the port thru which it would enter the reservoir is closed when the lever is moved from the released position.  Check how a master cyl works.

It may allow any air to rise to the master cyl so that when the lever is released, it immediately enters the reservoir.

[MtnRider]

With pressure in the system, the air bubbles would compress. Wouldn't the smaller bubble size move thru the hoses easier?

[okrider]

I swapped out the right caliper for the new one, tried swapping the left one, it kept leaking from the banjo bolt, pretty sure it was cross threaded and so that's junk.

But either way, I'm at square one right now, no leaks, tried reverse bleeding the right caliper, no air came out. The left one still has the speed bleeder, so going to switch that to a OEM one and reverse bleed that one, see if I get anything. Then if no pressure, rebuild the master again since that helped tremendously last time.

[Rubber_Snake]

Okrider,

I just had this thought (I don’t get many), but, is it possible, that when you rebuilt the calipers, you may have installed one of the seals in backwards?  Has this been brought up yet over these last 9 (now 10) pages?  I’ve never rebuilt the calipers myself, but I understand that if the seals are not in the correct direction, they will not keep pressure and leak.  I wonder if you haven’t been able to see fluid coming out of the calipers near the piston/pad area because the leak is so slight.  Maybe, just maybe, this is the problem? 

Ray

[Rubber_Snake]

I checked and saw that VJim did ask about this, and the conclusion was that they are square cut seals.  Is it possible that they are not square cut?  Is there somebody here that can confirm?  Perhaps checking with Murph?  The problem started when you rebuilt the calipers.  The caliper rebuild  must be the problem.  It sucks that one of the used calipers has a cross thread.  I think you’re so close to having your problem fixed. 

[okrider]

I can confirm they are square cut seals. I inspected both old and new seals to see if there's a direction to them. There's not

[okrider]

No real update, my clutch was leaking at the slave so I replaced the seal but it kept leaking so I ordered a used slave cylinder and that seems to have solved the problem. Back to brakes, I went back to the OEM bleeders on both calipers (keep in mind right is used off eBay and left is mine rebuilt). Reverse bled the left as I had reverse bled the right last time I touched the bike, then "rebuilt" the master with the same components again as that helped tremendously with feel last time, no such luck this time. Removed each caliper and inspected for leaks at pistons, no visible leaks or anything unlike my clutch slave which was making air bubbles as it leaked fluid

The clutch and brake levers feel about the same resistancewise the brake is slightly more difficult to pull but not by much, not enough to inspire confidence..

[okrider]

The new clutch slave is also leaking for some reason.. I'm going to put the new seal on the used slave I got to see if that helps.

In the mean time, did a test ride after much bleeding, let it sit with a ziptie, and I lost all pressure again. I wonder if it has to do with air in the lines expanding with engine heat and then shrinking when it cools. But I also ordered a left caliper, it's the one I couldn't change before as the one I got was damaged, so going to replace that to eliminate that possibility.